hermanntrude

the fumehood is a very wise investment. I'd say the best approach is to 1) consider not making chlorine at all 2) get a fume hood 3) consider not making chlorine at all again 4) consider doing it outside on a day with predictable low windspeeds and using a respirator 5) when you get a big whiff of chlorine and your throat hurts for a week, remember your lungs are damaged too, but you didn't feel that part, and don't blame us.

If there was only a single electron in the atom, the subshells would degenerate (all at the same energy as each other within each shell). However, as you get more electrons, the subshells start to split in energy. The s-subshells get closest to the nucleus, so they prevent the p- and d- orbitals from feeling the full impact of the attraction of the nucleus. This is called screening, or shielding. What this means is that the s-subshells have lower energy than the p-orbitals. The same is true for p- and d-subshells. To start with, for the 2s and 2p subshells, the difference is small, but it does mean the 2s subshell is filled first. When we get to the 3s, again we see it's lower than the 3p. The surprise is that the next subshell is the 4s, and not the 3d subshell. The 4s subshell is reduced in energy so much by its proximity to the nucleus that it actually ends up lower than the 3d subshell. but not by very much, which is why we get some weird electron configurations and other phenomena in transition metals. You average textbook contains a lot of useful diagrams and probably a better explanation as well.

I'm really not very happy about the respirator idea. Chlorine is revolting stuff. Ideally you'd be using a fume hood, or just not using chlorine at all. Liquid chlorine is mildly interesting but it's only really a greenish liquid. Respirators have a nasty habit of letting gases get around the sides. Don't for a second think that you are invulnerable just because you have one on. Make plans for what you will do with your chlorine when it's liquefied, and what you'll do if it gets spilled or accidentally released. Will you be risking anyone else's health? how can it be safely cleaned up?

when you reverse the reaction, you take 1/K when you double the reaction, you take K^2 when you half the reaction, you take square root(K) when you combine reactions, you multiply the Ks

I wrote something and then deleted it because it was stupid. sorry.

I think an exhibit is just showing something interesting off as something to look at, whereas an investigatory project is a presentation of the results of a series of experiments designed to investigate a particular hypothesis

icebergs are almost entirely fresh water. The blue ice is ice with no bubbles in it. Icebergs are made from snow, not sea. Sea ice is salty, but usually less salty than sea-water and the amount of salt depends on a number of things.

One answer I had on a paper in the chemistry exams I had to mark: the question showed a diagram of an electron configuration for nitrogen which contained a hund's rule violation. The question said "state why the following diagram represents an excited state for nitrogen". The answer was this: "because the nitrogen knows it's nearly Christmas."

I've been using tap water, and, strangely, none of my plants have died.

adding a solid to a buffer won't change the concentration of the buffer. However, as soluble solids go, sodium chloride is fairly inert.

Boyle's law is easy to demonstrate using a J-tube (google it). You don't have to use mercury, either, water will work fine. an important thing is that the tube should be quite wide, though.

i've seen all your video's. I appreciate them and enjoy them immensely. However, I don't recall that particular video explaining the effect I've observed above. By the way I have recently repeated the experiment using a ceramic crucible instead of a metal one to check the ferrous metal hypothesis mentioned above. The results are the same.

one piece of advice. ALWAYS read MSDS documents for every substance you plan to use. You can easily find these by typing (for instance) "boron MSDS" into google. as for your proposed reaction I have no idea if or how it will work

This was a new stainless steel container. I doubt anything was loose on it. I suspect that both para- and dia-magnetism are more complex than usually taught. I suspect that core electrons (most of the ones which are paired) ALWAYS display some diamagnetism, which in many cases cancels out the paramagnetism of the ocassional unpaired electrons in the valence shell. the exceptions, of course would be elements which had very few core electrons, so the diamagnetic effect wouldn't be enough to counteract the paramagnetic one. These elements would correlate nicely to the ones we usually restrict ourselves to in simple chemistry courses (the first three periods). This is just a hypothesis, of course, but I DID read somewhere that ALL substances are diamagnetic to some extent.

I actually have overturned physics: http://img191.imageshack.us/img191/7083/84102087.jpg

http://www.scienceforums.net/forum/showthread.php?t=40177

the skewer was wooden, and the crystals were deliberately chosen to be at least close to the same size.

antimony and bismuth also do that Merged post follows: Consecutive posts mergedas for chemicals with unusual properties, i ted to think of each substance as rather like a child... special in its own way, even if it is a toxic little bastard. Some of my favourites are: bismuth (non-toxic, despite being in an area of the periodic table filled with toxic elements, makes beautiful crystals, low melting point, very dense, repels magnets) diethyl ether: boiling point of 35°C, phenomenally high vapour pressure at room temperature, anaesthetic and flammable. heavy water: about 10% heavier than normal water, melts at 3.7°C and ice cubes made of it sink in normal water tritium: pretty much the only radioactive isotope I've ever owned, makes a good keychain which glows continuously for years iodine: very pretty crystals, very reactive, incredibly low melting and boiling points, bright purple. there are dozens more

OK let me explain my reasoning just so you don't think i'm crazy: I recrystallised some 99.99% pure bismuth to get some pretty pieces to show off. I also wanted to demonstrate diamagnetism to my students so I hung a skewer from a retort stand, by a string tied around its middle. I then attached a counterweight (clay) to one end and a lump of bismuth to the other. Because I figured it didn't matter if it was particularly pretty, so I used a crappy piece from the edge of the dish. When I approached it with a magnet it was attracted to it. I then repeated the experiment using a better-looking crystal, and this time it was repelled.

There's a popup which goes with it too, when you hover the mouse over it, it says

that's what's weird, though... it's supposed to be paramagnetic, because it has unpaired electrons. however no-one seems to be able to explain why they teach one thing to the students and ignore the complete opposite in nature. I might be mistaken about the paramagnetism in my experiment... it's not a foolproof experiment, i'm sure, but that's the way it seems.

did you read the thread or anything about bismuth? Most sources quote that bismuth is remarkably diamagnetic, and I (not uniquely) have shown it to be true using a torsional balance, but I have also noticed that when it isn't in the crystalline form which is so well known for being beautiful, it seems to exhibit paramagnetism.

nevertheless, according to the rules taught in first year degree courses, bismuth, due to its three unpaired electrons, should be para, not diamagnetic.

Seriously, my Dad On A PogoStick would involve some very serious injuries. That's not cool.

OK i helped you quite a lot with that one. I'd just like to remind you that you have to construct your own equations in this type of question so make sure you can see how i put that together. it may be worth reading the section in your textbook on grahame's law so you consolidate the knowledge. As for question 2, try solving the ideal gas law (in the form where you can use density as a variable) for M. This M will be the average M of all the atoms involved. from that you should be able to solve for the mole fraction by rearranging the equation for an average. I'm going to bed now so good luck with this one. good night!